The formation of joint connections between intersecting pipes or tubing without the use of couplings or other prefabricated fittings is a common industrial practice. Whether prepared on site or prefabricated, the usual procedure is to first form a radial aperture by punching or drilling through the wall of the recipient primary tube section. The secondary tubing is then laterally positioned in the aperture where the two are secured together by metal bonding applied about the opening.
To aid in controlling penetration of the secondary tubing within the bore of the primary tubing while providing a structurally convenient bonding surface, it has been common to form or apply an enlarged annular bead inwardly displaced from the insertable end of the secondary tube. The outboard end per se functions as a pilot to aid in placement of the tube within the drilled aperture.
While such joints formed in the foregoing manner have functioned with a reasonable degree of satisfaction in the end joint of which they become a part, certain limitations have been experienced. For example, it is sometimes difficult to obtain objective perpendicular alignment between the intersecting axes of the respective tube sections. Such misalignments may cause difficulties of assembly with remaining piping of the system yet to be added and can require considerable compensation elsewhere for rendering the system operable and fluid tight. Yet another difficulty has been flow obstruction attributed to pilot end penetration within the bore of the primary tube causing undesirable turbulence to occur. Any obstruction represents an energy loss and is of course a condition which should be avoided.